Apparatus for directing the sighting of guns



2 Sheets-Sheet-l w. ANDERSON APPARATUS FOR DIRECTING THE SIGHTING OF GUNS `Filed Jan. 16. 1926 YUV? xm am m@ nu H Bw .Rv

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April 12, 1927.

Patented Apr. 12, 1927.

UNITED STATES RAYMOND W. ANDERSON, OF MAPLEWOOD, NEW JERSEY.

APPARATUS FOR DIRECTIN Gr THE SIGHTING 0F GUNS.

Application led January 16, 1926.

This invention relates to apparatus for use in directing the sighting of guns and more particularly to apparatus for use in cases in which there is a high relative speed between the gun and the target, as in the case of anti-aircraft guns and the like.

An important object of the invention is to p-rovide means for computing and presenting automatically and continuously the elevation, fuse setting and azimuth readings required in gun re. i

Another object is to provide apparatus for the above purpose, performing computations based on lineal velocities. Such apparatus enables fire control to be conducted by indirect gun laying.

The problem of anti-aircraft gun fire may be approached in two ways; (l) by computations based on angular velocities; and (2) by computations based on lineal velocities. Furthermore, anti-aircraft fire control may be conducted either by direct or indirect gun laying. The instrument of the present invention performs computations based on lineal velocities and enables lire control to be conducted by indirect gun laying.

To succeed in anti-aircraft fire, that is, of directing a projectile on an aerial target, three quantities must be known: (l) the quadrant elevation for the gun; (2) the horizontal azimuth for the gun; the setting of the fuse or the like. Since the target is moving, these three elements may be changing constantly. One or more may be unchanged as in the case in which defiection remains unchanged due to the target flying along the line gun-target. According to the present invention readings are supplied continuously in such form that they may be transmitted to the gun layers and fuse Setters permitting projectile bursts or shell explosions to be located on or effec-- tively near the target.

Method of solution.

Part I. The horizontal range change of the target-From instruments now in use, such as altimeters, telemeters, and plotting apparatus, the following data may be obtained: horizontal range, altitude, velocity serial No. 81,864.

of the target. For convenience such quantities will be referred to hereinafter as R, A and V, respectively, and time as T.

The instrument of the present invention employs another element in computation, that is, the ano'le formed by the vertical plane passing tirough the line gun-target with the vertical plane passing through the longitudinal axis of the target. This angle, conveniently referred to as F, may be obtained by plotting apparatus or by estimating the angl-e, inasmuch as suli'icient accuracy has been obtained in this manner. Y

The following formula may now be considered:

R-i- (VXTXcos F):R1,

in which R is the horizontal range of a target at a given instant and R1 is a new horizontal range after an interval of time T has elapsed, T being preferably of such brevity that for practical results the arc of any curve generated by the horizontal projection of the targets movement may be considered as a straight line. Upon integration or solution of this formula continuously, the varying range R will be obtained continuously. This statement is made with the assumption that the target remains in one horizontal plane, or for practical purposes in approximately one horizontal plane.

Let it be assumed that two graphs have been constructed with units of range set off along the base and units of altitude set 0E at right angles to the base. On one graph are constructed trajectory curves at frequent angular intervals and appropriate to the material used and on the other or second graph are constructed time setter curves at frequent time intervals and appropriate to the fuse used, isopyre curves for burning fuse and isochrone curves for clock fuse.

If the aforesaid graphs are moved along their respective bases at such a velocity that the results of the continuously integrated formula,

R-l- (VXTXcos F) :En

are values of R1 corresponding to the graphs range graduation, and 1f indices are placed above the respective bases corresponding to FIS the altitude of the target, itwill be possible by means of the indices to identify- (1) the trajectory along which the target lies at any given instant;

(2) the fuse setter curve on which the target lies at that given instant.

Part II. Horizontal mage prediction,.- Depending on angle F, it may be necessary to re at a greater or less elevation with a fuse set at a longer or shorter time than identified as described in Part I. To meet this requirement a prediction element may be provided. Prediction of the position of the target at the end of the interval of time between the insta-nt a command is given to the gun for elevation and to cut or set the fuse and the instant the projectile bursts, depends upon the time required to manipulate gun and projectile or dead time, the time of fiight, the velocity of the target, and the angle F.

To the variable R obtained in Part I must be added or subtracted a distance given by the product V T cos F placement parallel to the bases across the moving graphs at any desired altitude. If such displacements correspond to the product,

V T cos F,

it will be possible by mea-ns of these movable indices to identify:

(1) the trajectory which the target will cross after T seconds;

(2) the fuse setter curve which the target will cross at the end of T seconds.

Pcart I I I Horizontal daim/utk Cmd prediction- By means of a goniometer the horiz'ontal azimuth of a. moving target may be obtained continuously. To render this information useful in anti-aircraft fire, an angular prediction is required to determine the firing to the right or left of the target by the angle in mils determined by the product quired sense at the right or left of the fixed index it will be possible to identify the azimuth in which the target will be found after T seconds.

Equations Sol/ved.

From the foregoing it will be seen that, to determine the proper directions for sighting the gun or guns, it is necessary to solve the following equations:

in which R, is the horizontal range at which a trajectory may be identified at the required altitude in order to place at or near the target a burst of a projectile, data for which is read T1 seconds after a target has left a point at a given known horizontal range Roand reaching that target T seconds after data is read from the instrument to set a fuse, the time T including dead time plus time of flight.

V T sin F Rk in which Az is the final azimuth determination, Azo is the original azimuth observed, Az1 is the additional angle due to the fiight of the target during the interval between the original observation and the reading of data for giving an order, and

VXTXsin F Rk being the prediction element in mils of the change in azimuth during the dead time and time of fiight of the projectile.

Other features and advantages will hereinafter appear.

In the drawings- Figure 1 is a top plan view of an approved form of apparatus for carrying out the present invention;

Figure 2 is an elevation of the apparatus shown in Figure 1;

Figure 3 is a diagramatic View illustrating the principles of operation; and

Fig. 4 is a diagram illustrating the manner of graduating the velocity scale.

As illustrated in the drawings the instrument, which includes a telescope 1, is supported by an upright or standard 2 having at its top a round table 3 provided at its center with a fixed worm gear 4 and also an upwardly extending pivot 5 which determines the axis of rotation of an instrument table 6. This table is supported by means of rollers 7 pivoted on brackets depending from table 6, and resting on the round table 3. Mounted on the lower ends of the shaft 8 -rotatably supported in table 6 is a Worm gear 10 which is a duplicate of gear 4, and these gears 4 and 10 are engaged respectively by worms 11 and 12 on a shaft 13 rotatably supported on brackets projecting down- (2) Az AZO j; A21 :I:

a y i ell) fil)

wardly from the table 6, and having at its outer end a crank 14. Turning of the crank 14 causes the table 6 to be turned and also the shaft 8 to be turned at the same angular rate but in the opposite direction. At the upper side of table 6, an azimuth scale 15 is secured to shaft 8 to turn therewith, said scale being graduated in mils. It will be evident that, as a result of turning the azimuth scale 15 and the table equally in opposite directions, the angular` position of the azimuth scale with reference to the ground, will be the same at all times irrespective of the angular position of the table.

Mounted on table 6 is .a constant speed motor 16, preferably a spring motor with a governor, which is connected with the apparatus to be driven by means of a spur gear 17 meshing with a lspur gear 18 fixed on a shaft 19 carrying a friction disc or wheel 20 of which one face is pressed against the periphery of a friction wheel or disc 21 by means of a pin 22 and spring 23. Disc 21 is slidably mounted on a shaft 24 orthogonal to the shaft 19, being held against rotation relative thereto by means of a long keyway 25. By means to be described hereinafter the disc 21 may be shifted to vary the speed of rotation of the shaft 24 as driven by the constant speed motor 16. Motion is transmitted from the shaft 24 by means of a worm 26 thereon to a worm gear 27 fix-ed on a shaft 28 journalled in bearings 29. Slidably mounted upon shaft 28 is a cylindrical drum 30 which is held against rotation relative to the shaft 28 by means of a long key 31 fitting a suitable keyway in the drum 30. This drum is supplied with a fuse graph 33 and an eleva tion graph 32 to which reference will be mad-e hereinafter.

Provision is also made of a rectangular frame 34 swingable around the drum 30 and journalled on the shaft 28 near the bearings 29 so as not to interfere with movement of drum .along shaft 28. For the purpose of moving the drum 30 longitudinally it is provided at one end with a circular flange 35 projecting beyond the cylindrical surface and fitting into a notch in a block or unit 36 mounted on a screw shaft 37 journalled in and held against longitudinal movement by suitable bearings. The shaft 37 may be turned by any suitable means such as a crank 38. hlounted on the sides of the fram-e 34 are blocks 39 and 40 carrying respectively indices or pointers 41 and 42 for use in connection with the fuse graph 33 and the elevation graph 32 respectively. The position of hair line 35a on ange 35 may be so adjust-ed along the altitude scale 42at that indices 33 and 32 will have position corresponding with the altitude of the target. The angular position of the frame is determined by means to be described hereinafter.

At the same end of the table 6 as motor 16 are a driving spur gear 43 and two driven spur gears 44 and 45 on opposite sides of the gear 43. These gears are mounted on shafts which extend downwardly into bearings fiXed in table 6. The shaft 46 of the gear 43 extends above the gear and is provided with opposite projections 47 fitting into notches at opposite sides of the hollow barrel of a removable key 48 having an operating handle 49 at the top thereof, the hollow barrel of the key being of such internal diameter as to fit over the upper end of the shaft 46. The shafts of the gears 44 andl 45 do not project above their upper faces and these gears are provided respectively with pins 50 and 51 projecting respectively into a slot 52 in a carriage 53 and into a slot 54 in a carriage 55. These carriages are mounted to slide on parallel rods 56 supported at their ends in brackets 57 and the slots 52 and 54 are at right angles to the path of movement of carriages 53 and 55.

.The carriage 53 is provided with an upright pin 58 on which is pivoted one end of a lever 59 provided in the intermediate part thereof with a longitudinal slot which receives a fulcrum pin 60 in a block or nut 61 slidable between two guides 62 and threaded upon a screw shaft 63 journalled in brackets 64 and provided at one end with a bevel gear 65 meshing with a bev-el gear 66 on .a shaft 67 actuable by a knob 68 to set the block 61 at a suitable position along a velocity scale 62 on the front guide 62. The shaft 67 is also provided with a bevel gear 69 meshing with a bevel gear 7 O on a screw shaft 71 to set a block or nut 72 and a pin 73 to positions corresponding to those of block 61 and pin 60. At the Iend distant from the pin 58 the lever 59 is slotted to receive the shank of a pin 74 fixed into a block 75 slidable on a bar 76.

Velocity scale 62 is graduated as follows (Figure 4) Represented lineally is a unit of velocity, a..

a/ all a equals equals -3- Represented lineally is the cosine of zero degrees, or one, by the line b.

The upper end of a is connected with the lower end of Z).

Since a parallel to the base of a triangle divides the sides proportionally,

d u b (The triangle meant is that having sides tel-CZ, Z -{A, and a side extending downwardly and to the right and considered as the base. Obviously the line parallel to this base and dividing the horizontal side in the ratio of c to (l, divides the vertical side in the same proportion).

etc.

Since a and A by construction are parallels between parallels, a and A are equal and c equals (EL multiplied by d.

similarly, c' equals 9,; multiplied by a', c',

equals a-,g-l multiplied by d", etc. ad. inf.

The distances a, a', a are proportional to the velocity and are equal respectively to c c c gb, gli), -/l

Since a is equal to 2a and a is equal to 3a; then b represents the cosine of the zero value of F and is equal to one. In other words is selected as a unit. Then, if we selecta distance a as representing a certain number of units of velocity and draw a line from the top of a to the bottom of b, the point of intersection with the horizontal line is the point on the scale 62 which is marked with the number of units represented by a. By laying off other distances (such as a and a) in proper ratio to a and drawing lilies from the upper ends of suoli lines to the lower end of b, the markings for other points on the scale 62 may be determined.

Now, if the angle F'is such as to have the cosine b1 and this is to be multiplied by velocity a, a line is drawn from the lower end ot' b1 through the proper point (the intersection of the horizontal line with the inclined line from the top of a to the bottom of b) and continued until it intersects the line along which a is laid off.

Then

b and a1=1-21 a=a cos F.

(Distance c does not represent the velocity. Distance a represents the velocity and the point at o distance from the foot ot a is the graduation on the velocity scale used in computing multiplication ot' the velocity a by cosilies of different values of angle F.)

lt liiay be considered that a and b are plus. Minus a aiid b may be treated similarly.

To multiply any velocity, a, by the cosine,

' b1, of any angle F, from the graduation b1 (determined automatically by the position of pin 108) run a line through the joint correa, equals multiplied by a.

Otherwise expressed, a, units of velocity eqaul cosine F cosine zero degrees multiplied by velocity a, or a1 equals cosine of F multiplied by velocity a 1 Pivoted on the shank of the pin 74 above the slotted end of lever 59 is the end of a lever 77 having an intermediate slot 78 to receive a pivot pin 79 on a slidable block or nut 80 controlled in position by a screw shaft 81 connected by bevel gears 82 with ashaft 83 operable by a knob 84 to set the pin 79 to the proper position along a time scale 85. The time scale is graduated simi-V larly. to the method for graduating the velocity scale, time units taking the place of velocity units. Multiplication is eiiected as in the case of the product of velocity and cosine F. It may be noted that velocity multiplied by time gives distance. The shaft 83 is also provided with a bevel gear 86 which acts through a bevel gear 87 and screw shaft 88 to set a block 89 and pin 90 in positions corresponding with those of block 8O and pin 79.

At its other end the lever 77 is slotted to receive the shank of a screw 91 threaded into a block or nut 92 slidable on a bar 93.

Pivoted on the shank of said screw 91 above the slotted end of lever 77 is the end of a lever 94 having an intermediate longitudinal slot to receive a pin 95 in a slidable block or nut 96 controlled as to position by a: screw shaft 97 connected by bevel gears 9S with a shaft 99 operable by a handle 100 to set the pin 95 to the proper position along a range scale 100. The range scale is graduated similarly to the method for graduating the velocity scale, distance units taking the place of velocity units. It may be noted that distance multiplied by the re'- ciprocal of the range in thousands of the distance units gives mils. It will be observed that by shifting the position of pin 50 to such a position that, when gears 43, 44 and 45 are in mesh, the radius passing through it is at right angles to the radius passing through pin 51, a scale of the values of sine F is established in a manner similar to that in which is established the cosine F scale A plus a'nd minus convention is applied suitable to the clockwise or counterclockwise graduation of the gun sight. At its other end the lever 94 is slotted to receive The shank of a screw 101 threaded into a slidably mounted block 102 on bar 103. Secured to the block 102 is a rack 104 with a gear 105 rotatably mounted on sha'ft 8 which carries the azimuth scale 15. Rotatable with the gear 105 is an arm 106 which projects above and extends inwardly over the azimuth scale 15, the inwardly projecting' portion of tm4 arm being U-shaped and holding a hair line o1' fine wire 107 which serves as an index or pointer for reading the azimuth. It should be understood that the shifting of the wire 107 by the rack 104 serves to give a corrected azimuth reading.

The carriage 55 is provided with an upright pin 108 on which is pivoted one end of a lever 109 having intermediate its ends a slot 110 to receive the pin 73 and at its other end a slot to receive the shank of a screw 111 threaded into a block 112 slidably mounted on the bar 76 and connected with the friction disc 21 for shifting the same along the face of the friction disc 20. The connection between the block 112 and the friction disc 21 consists of a link 113 having a clamping device including a set screw 114 for adjusting the length of the link. The link 113 is also provided with a yoke engaging in a groove 114a in the hub of the disc 21.

Pivoted to the shank of the screw 111 above the slotted end of the lever 109 is a'. lever 115 which has at an intermediate part a longitudinal slot 116 to receive the pin 90 and at its other end a slot 117 to receive the shank of a screw 118 in a block 119 slidable on the bar 93 and carrying a rack 121 which meshes with a gear 120 on a shaft 122. The shaft 122 also carries a gear 123 identical with gea-r 121, which serves to actuate a rack 124 meshing with a gear 125 fixed to the frame 34.

The theory of operation of the instrument is substantially as follows: When the handle 49 of the removable key 48 is parallel to the telescope 1 and the parts are set to correspond to the flight of the target directly away from the instrument, the pin 50 is in its extreme left hand position (Fig. 3) and the corresponding radius is perpendicular to a line through the axes of the gears 43, 44 and 45. With thekey handle 49 in this position, the yradius of the gear 45 determined by the pin 51 points toward the axis of the gear 43. During the movement of the handle 49 the pins 58 and 108 will move along paths parallel to the line through the axes of the gears 43, 44 and 45 and of lengths equal to the diameters of the circles described by the pins 50 and 51 and the distances of the pins 58 and 108 from the centers of their paths will be proportional to the sine and cosine respectively of the angle F through which the handle 49 is turned.

Furthermore it will be evident by the principles of similar triangles that the mov-ement a of the screw 74 due to the movement b of the pin 58 is equal to Z) multiplied by c and divided by d where c is the length of the perpendicular from the pin 60 to the path of the screw 74 and CZ is the length of the perpendicular from the pin 60 to the path of the pin 58. If then the position of the pin 58 represents sin F, the position of the pin or screw 74 will represent V sin F in velocity, the position of the screw 91 will represent V T sin F in distance, and the position of 'the screw or pivot 101 will represent V T sin F R in mils and will determine the position of the index or'wire 107 adjacent the azimuth scale 15.

Similarly the position of the pin 108 represents cos F, the position of the scr-ew or pivot 111 represents V cos F and the position of the screw or pivot 118 `represents V T cos F the position of the frame 34 being determined in accordance with the value of V T cos F and the rate of turning of the drum 30 being determined by the value of the quantity V cos F.

As the cylinder or drum 30 is rotated, the trajectory and fuse setter curves pass at velocity, V cos F, under the movable indices 41 and 42 employed to apply the horizontal range prediction element. The lineal representation of the product V T cos F is transmitted to the frame carrying the movable indices 41 and 42 employed to apply the horizontal range prediction element. The graphs if they have been placed under the movable indices at the graduation cor responding to the altitude A, will enable a reader to obtain elevation and fuse setting data continuously during rotation of the cylinder at velocity corresponding to V cos F.

The operation of the instrument will now be described. The instrument is set up in a location near the guns and the motor 16 started. Crank 14 is then operated to direct the telescope 1 on the target and to hold it thereon. Horizontal range is read from a telemeter and set by means of a crank 126 connected with the shaft 24, the worm gear 27 being brought to such a position that the proper range indication on a drum 127 attached to the gear 27 appears under a fixed pointer 128. The altitude of the target is read from an altimeter and set by means of crank 38 which shifts the drum 30 to bring an index, such as a hair line 35a, on the fiange 35, into proper position along either one of two altitude scales 42a on the sides ot' the frame 34 so that indices 41 and 42 will correspond with the altitude on graphs mounted on drum 30. All of these settings are made as nearly simultaneously as possible. v

Index 49 is maintained parallel to the longitudinal axis of the target, following changes due to variations in the targets course and to the varying orientation of table 6. The velocity of the target, obtained by measurement plottingor estimation, is set on velocity scale 62', the time of ilight read on the fuse graph 33 is set on the time scale 85, and the range read on range graduation mounted on .drum 3() is set on range scale 100 which is graduated to correspond to the reciprocal of the range.

As changes in the data appear on the scales of the instrument, appropriate changes are made in the settings of other parts. If the velocity changes, corresponding chang-es are made in the setting in connection with scale 62.

Three readings are taken when an automatic signal indicating the period between rounds is given. (It is convenient to have this period equal to dead time, four to six seconds for example.)

One reading is made on the graph of trajectory graph 33 against the movable index 42 for that graph, and such reading is transmitted to the gun layer for elevation who elevates the gun to the angle indicated.

Another reading is made on the graph 33 of fuse setter curves against the movable index 41 for that graph, and such reading is transmitted to the operator of the fuse setter scale, the fuse being lset according to that data and the projectile placed in the gun.

A third reading is made on the azimuth scale 15 against the movable index 107 for that scale. It is transmitted to the gun layer for azimuth who lays the gun for the azimuth indicated.

The projectile is discharged when the next automatic signal is given. The operation is then repeated for the next round. Errors of range are corrected by the operation in the required sense of crank 126 and errors of altitude bycranlr 38. Errors of'deflection may be corrected either by a corrector on the telescope or on the gun itself.

IVind and drift, as iniiuencing deflection are corrected for by any of the methods now practiced in anti-aircraft fire. Wind correction affecting elevation and fuse Isetting may be computed and allowed forin advance as now practiced. A

It should be understood that the disclosure of the invention is merely illustrative and that various changes may be made in the structure and operation without departing from the spirit and scope of the invention.

I-Iaving thus described my invention, I claim:

1. In apparatus for directing gun tire, means for setting the apparatus in accordance with an angle F, a velocity V and time T, a firing-data graph, an index cooperating with said firing-data graph for taking readings thereon, means for effecting a relative shifting of said graph and said index, and means for computing V T cos F and changing the relative positions of the firing-data graph and index accordingly for applying a prediction correction to the reading from the firing-data graph, where V is the velocity of the target, T is the sum of dead time and time of iight of the projectile, and F is the horizontal angle of flight of the target with reference to the horizontal projection of the line gun-target.

2. In apparatus for directing gun fire, means for setting the apparatus in accordance with an angle F and a velocity V,-a trajectory graph, a fuse-setter graph, indices cooperating respectively with said trajectory graph and said fuse-setter graph, means for eii'ecting a uniform and continuous relative shifting between said graphs and said indices, and means for computing V cos F and varying accordingly the relative shifting of said graphs and said indices, V representing velocity of target and F the horizontal angle of fiight of target with reference to the horizontal projection of the line gun-target.

3. In apparatus for directing gun fire, an azimuth scale, an azimuth index to cooperate with said scale, and means to vary the relation between said scale and said index comprising means for computing lineally the sine of the horizontal angle of flight with reference to the horizontal projection of the line gun-target and computing lineally the product of said sine by V, T and I/Rk, V being the velocity of the target, T the sum of dead time and time ot flight of the projectile and R1. being a range value.

In testimony whereof I afiix my signature.

RAYMOND W. ANDERSON. 

